DNA Testing

Introduction

Recent advances in scientific knowledge have produced sophisticated analytical techniques surrounding DNA, whereby samples can be traced to specific individuals. This has particular practical value to criminal investigations, as DNA has been produced in court as evidence to help secure convictions; DNA matches are now so sensitive that according to statistical probability, only one person could have left the sample. The work in this field has obvious implications for other pursuits, including genealogy; the ability to connect branches of the family, often separated by both geographical and chronological distance, is only one possible use, alongside more prosaic activities such as determining paternity.

Yet until recently, the expense of analysis has prohibited the development of home test kits, basically because the more sophisticated comparisons were simply too costly to perform in the domestic market. Thankfully, the growth of companies across the world has driven prices down whilst enabling more wide-ranging tests to be developed, and now DNA testing is becoming an integral part of proving a link to a branch of the family, particularly when the paper trail runs cold.

About DNA testing

DNA testing can provide you with answers to a number of questions, such as proving a connection between individuals via a common ancestor, linking you to another branch of your family with a common surname, or even assessing your ethnic background. There are two main types of testing that can be undertaken - mitochrondrial DNA (mtDNA) passed down the maternal side of the family to both boys and girls (but only carried on through the female line) and useful for testing the general relatedness of individuals to one another; and Y chromosone DNA (Y DNA) passed from father to son in a distinctive pattern, and used to work out the level of relatedness through a common male ancestor. DNA testing can also be used in comparison with sample groups to determine a connection with a specific ethnic group.

In general, DNA test results make little sense on their own - they need to be viewed alongside either another individual to work out the Most Recent Common Ancestor, or against a group sample so you can see how you fit into the overall pattern. Many DNA sample databases are beginning to appear online, whilst companies that provide information on matches within their own records, subject to permission being obtained first.

Y DNA testing works by providing a list of markers (or loci) concerning your DNA sample. These can be compared to other samples from your family to determine how closely you share a common ancestor. The more markers that are tested, the more accurate a match you are likely to obtain, in terms of determining how many generations back the common ancestor is likely to be. In comparison, mtDNA tests examine regions on your maternal DNA and uses them to work out your halpogroup, which can be used to provide a breakdown of your own ethnic background, as well as general relatedness to distant ancestors - which can be interesting if you are looking to prove a connection to a branch of your family which shares a common surname.

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About the author

Dr Nick Barratt worked at the Public Record Office (now The National Archives, or TNA) from 1996 to 2000, with the family history team. He has given many talks on family history, and has written frequently for the TNA's genealogy journal, Ancestors. He has worked for the BBC as a specialist researcher on programmes such as 'One Foot in the Past','The People Detective' and 'Who Do You Think you Are?'.